Pipe systems frequently use check valves which are biased to a closed position unless they are opened by a force sufficient to overcome the force biasing a flapper valve into its closed position. In larger pipe sizes, in particular, the installation and maintenance of such check valves can be difficult, due to the cost of components as well as their size and related difficulties in handling and/or accessing the components.
One valve which has previously been used in such installations is a thin, short length valve that fits between pipe flanges, called a wafer check valve. Another valve which has been used is a standard check valve with a flange on both ends which are secured to the pipe flanges.
Wafer check valves have the advantage of being relatively short in axial length (e.g., between two and three inches), but require that they be removed from the pipeline for service and maintenance. Such removal is not only difficult and time consuming, but then replacing a valve in the gap between pipe segments can be difficult and time consuming as well (e.g., the pipe segments might move when an old valve is removed and then be difficult to align when putting another valve between them).
Standard check valves have in some instances included service ports on their side, which allow access into the valve for service and maintenance without removing the body of the valve from between the pipe segments. However, in order to allow such access, such valve must be substantially bigger (e.g., twelve inches long) so that the service port is large enough for the maintenance worker to be able to reach inside and do the required work (e.g., to replace parts or to remove debris). This much larger valve thus costs more, and still can make repair work clumsy for a worker reaching inside a one foot wide opening.
The present invention is directed toward overcoming one or more of the problems set forth above.